Development of an In-Situ, Microspectrometer-Based Sensor for Monitoring Carbon Fiber Curing

Real-time monitoring is critical for process optimization and quality control in the manufacturing of advanced materials such as carbon fiber. This work details the development and validation of a compact, high-stability spectroscopic sensor system designed for this purpose, architected around a LIGA-fabricated spectral chip. The system's performance was evaluated by applying it to the in-situ monitoring of the thermal stabilization of polyacrylonitrile (PAN) precursors. The sensor's effectiveness was quantitatively demonstrated by its ability to track key process indicators using its direct raw signal. Specifically, it resolved a 26.24 nm redshift of the photoluminescence (PL) peak (from 849.93 nm to876.19 nm) during initial heating. It also tracked dynamic changes in raw PL intensity during an isothermal hold and measured a 33.3% drop in signal intensity upon final curing. The system's stability and repeatability were further validated through statistical analysis of the raw signal, showing a low coefficient of variation CV < 3 %. The ability to quantify these transformations using direct raw data validates the developed sensor as an effective tool for in-situ monitoring.